Among them, most UPC codes can be found.
Requiring every bit width to be read precisely basically nullified the Delta C advantage except for the Delta C reference measurement.
Only the strange character set and the size of the label remains as a shadow of the Delta C code. The size was still that calculated for pure Delta C.
If the label size had been properly recalculated, taking into account the required bar width measurements the label would have been far too large to be acceptable. Mechanical engineering and electronic circuit design commonly require worst case designs using known tolerances. Many engineers working with bar codes had little experience with such things and used somewhat intuitive methods. Each UPC-A barcode consists of a scannable strip of black bars and white spaces above a sequence of 12 numerical digits.
No letters , characters or other content of any kind may appear on a UPC-A barcode. There is a one-to-one correspondence between digit number and strip of black bars and white spaces, i.
The first digit L indicates a particular number system to be used by the following digits. The last digit R is an error detecting check digit , that allows some errors to be detected in scanning or manual entry.
The guard patterns separate the two groups of six numerical digits and establish the timing. UPC-A barcodes can be printed at various densities to accommodate a variety of printing and scanning processes. The significant dimensional parameter is called x-dimension width of single module element.
The width of each bar space is determined by multiplying the x-dimension and the module width 1, 2, 3, or 4 units of each bar space. The x-dimension for the UPC-A at the nominal size is 0. Nominal symbol height for UPC-A is The bars forming the S start , M middle , and E end guard patterns, are extended downwards by 5 times x-dimension, with a resulting nominal symbol height of This also applies to the bars of the first and last numerical digit of UPC-A barcode.
A quiet zone, with a width of at least 9 times the x-dimension, must be present on each side of the scannable area of the UPC-A barcode. Each digit is represented by a unique pattern of 2 bars and 2 spaces. The bars and spaces are variable width, i. A complete UPC-A is 95 modules wide: The S start and E end guard patterns are 3 modules wide and use the pattern bar-space-bar , where each bar and space is one module wide.
The M middle guard pattern is 5 modules wide and uses the pattern space-bar-space-bar-space , where each bar and space is also one module wide. In addition, a UPC-A symbol requires a quiet zone extra space of 9 modules wide before the S start and after the E end guard patterns.
The UPC-A's left-hand side digits the digits to the left of the M middle guard pattern have odd parity, which means the total width of the black bars is an odd number of modules. On the contrary, the right-hand side digits have even parity. Consequently, a UPC scanner can determine whether it is scanning a symbol from left-to-right or from right-to-left the symbol is upside-down. After seeing a S start or E end guard pattern they are the same, bar-space-bar , whichever direction they are read , the scanner will first see odd parity digits, if scanning left-to-right, or even parity digits, if scanning right-to-left.
When confronted with an upside-down symbol, the scanner may simply ignore it many scanners alternate left-to-right and right-to-left scans, so they will read the symbol on a subsequent pass or recognize the digits and put them in the right order. There is another property in the digit encoding. The right-hand side digits are the optical inverse of the left-hand side digits, i. The UPC includes a check digit to detect common data entry errors. For example, in a UPC-A barcode " x 12 ", where x 12 is the unknown check digit, x 12 may be calculated by:.
The check digit equation is selected to have reasonable error detection properties see Luhn algorithm. As the UPC becomes technologically obsolete, it is expected [ by whom? To allow the use of UPC barcodes on smaller packages, where a full digit barcode may not fit, a 'zero-suppressed' version of UPC was developed, called UPC-E, in which the number system digit, all trailing zeros in the manufacturer code, and all leading zeros in the product code, are suppressed omitted.
With the manufacturer code digits represented by X's, and product code digits by N's, then:. This expanded the number of unique values theoretically possible by ten times to 1 trillion. EAN barcodes also indicate the country in which the company that sells the product is based which may or may not be the same as the country in which the good is manufactured. The three leading digits of the code determine this, according to the GS1 country codes.
This does not change the check digit. All point-of-sale systems can now understand both equally. From Wikipedia, the free encyclopedia. This article duplicates the scope of other articles , specifically, Barcode History.
Please discuss this issue on the talk page and edit it to conform with Wikipedia's Manual of Style. Retrieved April 28, Punched cards to bar codes: University of Maryland Alumni Association.
The University of Maryland. Archived from the original on After graduating from Maryland in , George Laurer joined IBM as a junior engineer and worked up the ranks to senior engineer. In , he returned to the technical side of engineering and was later assigned the monumental task of designing a code and symbol for product identification for the Uniform Grocery Product Code Council. His solution—the Universal Product Code—radically changed the retail world.
Since then, he has enhanced the code by adding a 13th digit. Retrieved 21 January Barcode reader Barcode printer. Academy of Technology Centers for Advanced Studies: Watson — Thomas Watson Jr.
Vincent Learson — Frank T. Cary — John R. Palmisano — Ginni Rometty —present. Alain Belda William R. Brody Kenneth Chenault Michael L. Spero Sidney Taurel Lorenzo Zambrano. Locate the UPC or bar code. The UPC bar code of an item is usually found printed on the label or package of an item. Because the bar code allows fast product entry at the cash register, this information is always found in an easily accessible spot on the outside of a product.
In some cases, such as clothing items, it is printed onto a removable tag. In other instances, it is printed onto the product itself.
If the bar code isn't immediately visible, check the back and underside of the product. Write down the UPC number. In addition to the black-and-white bar code, there should also be a number. This number is the same number that the bar code represents, but the bar code presents this number in a machine-readable format. The UPC number will usually be either eight or 12 digits in length, but 13 digit codes are not uncommon.
If the number is not the correct length or if it contains characters other than regular numbers, it's not a UPC bar code number. Check the UPC in an online database. While retailers will access paid UPC databases for their bar code scanning and recognition systems, there are several free options available to individuals.
Barcode Lookup helps you fill in the gaps for missing product barcodes. Just run a search by product and brand name or manufacturer part number (MPN) to find the barcodes . Barcode database sites or apps search the internet for information pertaining to the particular barcode number that has been entered or scanned. The information that is returned is generally company name and/or contact details, relevant product information or even where you are able to purchase a product . Scandit's UPC lookup tool searches our product database for any given UPC code. Scandit's solutions help bring barcode scanning technology to any industry.